The HTML 4. For the class attribute, there is no such limitation. HTML5 gets rid of the additional restrictions on the id attribute. This means the rules that apply to values of class and id attributes are now very similar in HTML5. Although that probably sounds boring, this actually is pretty cool. In HTML 4. Heck, you could even use a brainfuck program as a classname:.
After all, the possibilities are endless :. In HTML5, you can take all of these groovy classnames and use them as values for id attributes.
Yes, HTML5 is that awesome. I remade the same demo page as before to use id s instead of class es. Writing CSS for this markup is tricky.
Doing so will cancel the meaning of special CSS characters and allows you to refer to characters you cannot easily type out, like crazy Unicode symbols. Mathias, is this backwards compatible? Or do older browsers just ignore ID s like that? And what does it do for semantics? My second book — Sass and Compass for designers. Working with lists and each loops in Sass with the index and nth function. Hi Ricardo, Yes, all still holds true. Thanks for the info and update Ben.
Can you make a reduction on CodePen or similar? Leave a Reply Cancel reply Your email address will not be published. Below is the core syntax for CSS. The sections that follow describe how to use it. Appendix G describes a more restrictive grammar that is closer to the CSS level 2 language. Parts of style sheets that can be parsed according to this grammar but not according to the grammar in Appendix G are among the parts that will be ignored according to the rules for handling parsing errors.
The "unused" production is not used in CSS and will not be used by any future extension. It is included here only to help with error handling. See 4. Note, however, that a comment before or within the charset rule disables the charset. The token S in the grammar above stands for white space. Keywords have the form of identifiers. Keywords must not be placed between quotes " It is a string. Other illegal examples: Illegal example s :.
Such vendor-specific extensions should have one of the following formats:. For example, if XYZ organization added a property to describe the color of the border on the East side of the display, they might call it -xyz-border-east-color. An initial dash or underscore is guaranteed never to be used in a property or keyword by any current or future level of CSS. Thus typical CSS implementations may not recognize such properties and may ignore them according to the rules for handling parsing errors.
However, because the initial dash or underscore is part of the grammar, CSS 2. First, inside a string , a backslash followed by a newline is ignored i. Outside a string, a backslash followed by a newline stands for itself i. Second, it cancels the meaning of special CSS characters. Any character except a hexadecimal digit, linefeed, carriage return, or form feed can be escaped with a backslash to remove its special meaning.
Style sheet preprocessors must not remove these backslashes from a style sheet since that would change the style sheet's meaning. Third, backslash escapes allow authors to refer to characters they cannot easily put in a document. In this case, the backslash is followed by at most six hexadecimal digits It is undefined in CSS 2. If a character in the range [a-fA-F] follows the hexadecimal number, the end of the number needs to be made clear.
There are two ways to do that:. In fact, these two methods may be combined. Only one white space character is ignored after a hexadecimal escape. Note that this means that a "real" space after the escape sequence must be doubled. If the number is outside the range allowed by Unicode e.
If the character is to be displayed, the UA should show a visible symbol, such as a "missing character" glyph cf. Note: Backslash escapes are always considered to be part of an identifier or a string i. There are two kinds of statements: at-rules and rule sets. There may be white space around the statements. At-rules start with an at-keyword , an ' ' character followed immediately by an identifier for example, ' import', ' page'.
An at-rule consists of everything up to and including the next semicolon ; or the next block, whichever comes first. CSS 2. The second ' import' is illegal according to CSS 2. The CSS 2. In the following example, the second ' import' rule is invalid, since it occurs inside a ' media' block.
Instead, to achieve the effect of only importing a style sheet for 'print' media, use the import rule with media syntax, e. Single ' and double quotes " must also occur in matching pairs, and characters between them are parsed as a string. See Tokenization above for the definition of a string. Here is an example of a block. Note that the right brace between the double quotes does not match the opening brace of the block, and that the second single quote is an escaped character , and thus does not match the first single quote:.
In between there must be a list of zero or more semicolon-separated ; declarations. A selector always goes together with a declaration block. When a user agent cannot parse the selector i. However, since it is not known if the comma may acquire other meanings in future updates of CSS, the whole statement should be ignored if there is an error anywhere in the selector, even though the rest of the selector may look reasonable in CSS 2.
Here is a more complex example. JavaScript can access an element with a specific id with the getElementById method:. We just launched W3Schools videos. Get certified by completing a course today! If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:.
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